Cross-education effects of balance training in individuals with chronic ankle instability

Individuals with chronic ankle instability (CAI) often experience deficits in balance, hip strength, and lumbopelvic stability. Unilateral balance training can lead to improved balance in the contralateral limb, but it is unknown if similar cross-education effects occur for hip strength and lumbopelvic stability. Our purpose was to determine if unilateral balance training improved balance, hip strength, and lumbopelvic stability of the contralateral limbs in individuals with CAI.

Using a randomized-controlled trial, 30 individuals with CAI were separated into control (CON) and balance (BAL). Uninvolved limbs underwent testing at baseline and post-intervention. We tested balance with the star excursion balance test in anterior (SEBT-ANT), posterolateral (SEBT-PL), and posteromedial (SEBT-PM) directions. We tested hip strength with a handheld dynamometer in extension (EXT), abduction (ABD), and external rotation (ER). We tested lumbopelvic stability with a unilateral hip bridge. After baseline, BAL completed an 8-week balance training program on the involved limb. CON did not participate in the intervention. Two-way repeated measures ANOVAs analyzed effects of group and time on each outcome. Cohen's d effect sizes analyzed each group's changes from baseline to post-intervention.

Eleven participants discontinued the study (5 CON, 6 BAL) before completion. There were significant group-by-time interactions for SEBT-PL (P = 0.03) and hip bridge (P = 0.03). BAL had moderate to large effect sizes for SEBT-PM (d = 0.69 [-0.06,1.41]), SEBT-PL (d = 0.87 [0.10,1.60]), EXT (d = 0.73 [-0.02,1.45]), ABD (d = 0.79 [0.03,1.51]), and hip bridge (d = 0.83 [0.07,1.55]).

A balance training program for limbs with CAI led to contralateral improvements in balance, hip strength, and lumbopelvic stability.